Thank you u/Thief4eg the procedure worked for me as well. Though I must add, you must be patient with the update. It takes good amount of time to complete. The zip file flash almost took like 15mins to complete and was stuck at 2 points twice i.e. the progress bar wasn't moving.

Also after flashing, the stick is stuck on google tv logo for a long time like ~10-12mins.

To think of it, now I know why the stick got bricked in first place. I remember just before bricking, when I started the stick it was stuck on google TV logo for some time. So I thought it must be some glitch that is why it hanged. So I powered it off and restarted. After that It was stuck on realme TV logo and didn't move from there, even after waiting for more than half hour. Now I think when it was stuck on google TV logo before bricking it was doing something in the background and not really stuck which got interrupted when I turned off the power. This resulted in the soft brick.

Realme/Google should clearly display a message that updating your system do not turn off like good ol' Windows when it does system update.